1 files changed, 89 insertions, 0 deletions
diff --git a/src/util/rand_sleep.c b/src/util/rand_sleep.c
new file mode 100644
index 0000000..69a8cc8
--- /dev/null
+++ b/src/util/rand_sleep.c
@@ -0,0 +1,89 @@
+/*++
+/* NAME
+/*	rand_sleep 3
+/* SUMMARY
+/*	sleep for randomized interval
+/* SYNOPSIS
+/*	#include <iostuff.h>
+/*
+/*	void	rand_sleep(delay, variation)
+/*	unsigned delay;
+/*	unsigned variation;
+/* DESCRIPTION
+/*	rand_sleep() blocks the current process for an amount of time
+/*	pseudo-randomly chosen from the interval (delay +- variation/2).
+/*
+/*	Arguments:
+/* .IP delay
+/*	Time to sleep in microseconds.
+/* .IP variation
+/*	Variation in microseconds; must not be larger than delay.
+/* DIAGNOSTICS
+/*	Panic: interface violation. All system call errors are fatal.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <myrand.h>
+#include <iostuff.h>
+
+/* rand_sleep - block for random time */
+
+void    rand_sleep(unsigned delay, unsigned variation)
+{
+    const char *myname = "rand_sleep";
+    unsigned usec;
+
+    /*
+     * Sanity checks.
+     */
+    if (delay == 0)
+	msg_panic("%s: bad delay %d", myname, delay);
+    if (variation > delay)
+	msg_panic("%s: bad variation %d", myname, variation);
+
+    /*
+     * Use the semi-crappy random number generator.
+     */
+    usec = (delay - variation / 2) + variation * (double) myrand() / RAND_MAX;
+    doze(usec);
+}
+
+#ifdef TEST
+
+#include <msg_vstream.h>
+
+int     main(int argc, char **argv)
+{
+    int     delay;
+    int     variation;
+
+    msg_vstream_init(argv[0], VSTREAM_ERR);
+    if (argc != 3)
+	msg_fatal("usage: %s delay variation", argv[0]);
+    if ((delay = atoi(argv[1])) <= 0)
+	msg_fatal("bad delay: %s", argv[1]);
+    if ((variation = atoi(argv[2])) < 0)
+	msg_fatal("bad variation: %s", argv[2]);
+    rand_sleep(delay * 1000000, variation * 1000000);
+    exit(0);
+}
+
+#endif